Stapling device with a gap locking member

ABSTRACT

A tool assembly includes an anvil and a cartridge assembly pivotally coupled to one another. A locking member is rotatably supported on a distal portion of the cartridge assembly and positioned for receipt in a bore defined in a distal portion of the anvil. The locking member is operably coupled to a sled for advancing staples from the cartridge assembly. Advancement of the sled rotates the locking member relative to the bore to approximate the distal portions of the anvil and cartridge assembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. Provisional Application No. 62/913,961, filed on Oct. 11, 2019, the entire contents of which being incorporated by reference herein.

BACKGROUND 1. Technical Field

This disclosure is directed to a surgical stapling device and, more particularly, to a linear surgical stapling device having a tool assembly that defines a tissue gap and includes a locking member to maintain the tissue gap during firing of the stapling device.

2. Background of Related Art

Surgical stapling devices are commonly used during a variety of surgical procedures to staple and/or cut tissue. Stapling and cutting of tissue can be accomplished more quickly using surgical stapling devices than can be accomplished using traditional suturing techniques. In addition, endoscopic stapling devices can be used to perform less invasive surgical procedures than possible using traditional suturing techniques. As such, the use of surgical stapling devices to perform certain surgical procedures to reduce patient trauma and improve patient recovery times is desirable.

Typically, linear endoscopic surgical stapling devices include a tool assembly that includes a staple cartridge and an anvil assembly that are movable in relation to each other between open and clamped positions. The staple cartridge defines a plurality of staple pockets that receive staples and the anvil assembly defines a plurality of staple deforming pockets. When the tool assembly is in the clamped position, the staple deforming pockets of the anvil assembly are aligned with the staple pockets of the staple cartridge such that legs of the staples are received and deformed within the staple deforming pockets when the stapling device is fired. The staple cartridge and the anvil assembly must be properly aligned to effect proper staple formation.

Generally, the staple cartridge and the anvil assembly have proximal ends that are secured to each other by a pivot member such that the staple cartridge and the anvil assembly can be pivoted from the open position in which distal ends of the staple cartridge and the anvil assembly are spaced from each other to the clamped position in which the staple cartridge and the anvil assembly are in juxtaposed alignment. During firing of the staples from the staple cartridge, forces on the staple cartridge and the anvil assembly for firing the staples tend to deflect the staple cartridge and anvil assembly outwardly away from each other. In certain stapling devices, a knife bar is provided that includes upper and lower beams that engage the anvil assembly and staple cartridge to minimize deflection of the anvil and cartridge assemblies during firing.

SUMMARY

One aspect of this disclosure is directed to a tool assembly including an anvil, a cartridge assembly, a sled, and a locking member. The anvil and the cartridge assembly each have a proximal portion and a distal portion. The proximal portion of the cartridge assembly is pivotally coupled to the proximal portion of the anvil. The distal portion of the anvil defines a bore therein. The sled is slidably received in the cartridge assembly and configured to move from a proximal position to a distal position to advance staples from the cartridge assembly. The locking member is rotatably supported on the distal portion of the cartridge assembly and positioned for receipt in the bore. The locking member is operably coupled to the sled, such that advancement of the sled from the proximal position toward the distal position rotates the locking member relative to the bore to approximate the distal portions of the anvil and cartridge assembly.

In aspects, the locking member may have an extension having a threaded outer surface. The bore in the distal portion of the anvil may be defined by a threaded inner surface configured to threadedly engage the threaded outer surface of the extension of the locking member.

In aspects, the anvil and cartridge assembly may be movable between an expanded position, in which the extension of the locking member is spaced from the bore in the anvil, and a first approximated position, in which the threaded outer surface of the extension of the locking member is engaged with the threaded inner surface of the anvil.

In aspects, the anvil and cartridge assembly may be configured to move from the first approximated position to a second approximated position in response to rotation of the locking member while the threaded outer surface of the locking member is engaged with the threaded inner surface of the anvil.

In aspects, the tool assembly may further include a tether having a proximal end portion coupled to the sled, and a distal end portion disposed about the locking member, such that translation of the sled rotates the locking member via the tether.

In aspects, the locking member may have a barrel portion rotatably supported in the cartridge assembly. The distal end portion of the tether may be fixed about the barrel portion.

In aspects, the tool assembly may further include a biasing member received in the barrel portion and coupled to the cartridge assembly. The biasing member may be configured to urge the tether in a distal direction.

In aspects, the locking member may be spring-biased to urge the tether in a distal direction.

In aspects, the tether may be a looped band defining a plurality of apertures. The locking member may have a plurality of circumferentially spaced protuberances configured for receipt in the corresponding plurality of apertures.

In aspects, the sled may have a pin extending therefrom and received in an aperture of the plurality of apertures, such that translation of the sled moves the band along a looped path.

In aspects, the distal portion of the anvil may have a tissue dissector, and the tissue dissector may define the bore.

In accordance with another aspect of the disclosure, a surgical stapling device is provided and includes a handle assembly, an elongated body extending distally from the handle assembly, a drive shaft, and a tool assembly. The handle assembly includes a trigger, and the drive shaft has a proximal end portion operably coupled to the trigger. The tool assembly is coupled to a distal portion of the elongate body and includes an anvil, a cartridge assembly, a tether, and a locking member. The anvil and cartridge assembly each has a proximal portion and a distal portion. The proximal portion of the cartridge assembly is pivotally coupled to the proximal portion of the anvil between an expanded position and an approximated position. The distal portion of the anvil defines a bore therein. The tether has a proximal end portion coupled to a distal end portion of the drive shaft. The locking member is rotatably supported on the distal portion of the cartridge assembly and positioned for receipt in the bore. The tether has a distal end portion disposed about and coupled to the locking member, such that when the cartridge assembly and anvil are in the approximated position, advancement of the drive shaft rotates the locking member relative to and within the bore to approximate the distal portions of the anvil and cartridge assembly.

In aspects, the locking member may have an extension having a threaded outer surface. The bore in the distal portion of the anvil may be defined by a threaded inner surface configured to threadedly engage the threaded outer surface of the extension of the locking member when the anvil and cartridge assembly are in the approximated position.

In aspects, in the expanded position, the extension of the locking member may be spaced from the bore in the anvil, and in the approximated position, the threaded outer surface of the extension of the locking member may be engaged with the threaded inner surface of the anvil.

In aspects, the locking member may have a barrel portion rotatably supported in the cartridge assembly. The barrel portion may have the distal end portion of the tether fixed thereabout.

In aspects, the tool assembly may further include a biasing member received in the barrel portion and coupled to the cartridge assembly. The biasing member may be configured to urge the tether in a distal direction.

In aspects, the locking member may be spring-biased to urge the tether in a distal direction.

In aspects, the tether may be a looped band defining a plurality of apertures. The locking member may have a plurality of circumferentially spaced protuberances configured for receipt in the corresponding plurality of apertures.

In aspects, the tool assembly may further include a sled slidably received in the cartridge assembly. The sled may interconnect the distal end portion of the drive shaft and the proximal end portion of the tether. The sled may be configured to move from a proximal position to a distal position to advance staples from the cartridge assembly in response to an actuation of the trigger.

In aspects, the locking member may be configured to rotate in response to movement of the sled between the proximal and distal positions.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the disclosed linear surgical stapling device including a tool assembly are described herein below with reference to the drawings, wherein:

FIG. 1 is a side perspective view of an exemplary embodiment of the disclosed stapling device including a tool assembly in an open position;

FIG. 2 is an enlarged perspective view of the tool assembly of the stapling device shown in FIG. 1 in the open position;

FIG. 3 is an exploded perspective view of the tool assembly shown in FIG. 2;

FIG. 3A is an enlarged view of the area of detail shown in FIG. 3 illustrating a locking member, a biasing member, and a channel of the cartridge assembly;

FIG. 4A is a cross-sectional view along the longitudinal axis of the tool assembly shown in FIG. 2 with the anvil and cartridge assembly in a first, approximated position;

FIG. 4B is an enlarged view of the area of detail shown in FIG. 4A illustrating the locking member of the cartridge assembly engaged with a threaded bore of the anvil;

FIG. 5 is a bottom perspective view of the cartridge assembly of the tool assembly shown in FIG. 4A, with parts removed, illustrating a locking member;

FIG. 6 is a cross-sectional view along the longitudinal axis of the cartridge assembly shown in FIG. 5 with a sled of the tool assembly in a distal position;

FIG. 7 is a cross-sectional view along the longitudinal axis of the tool assembly shown in FIG. 2 with the anvil and cartridge assembly in a second, approximated position;

FIG. 8 is an exploded perspective view of another exemplary embodiment of a tool assembly; and

FIG. 9 is a bottom perspective view, with parts removed, of a cartridge assembly of the tool assembly shown in FIG. 8.

DETAILED DESCRIPTION OF EMBODIMENTS

The disclosed surgical stapling devices will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure in virtually any appropriately detailed structure.

The present disclosure provides a tool assembly including a locking member rotatably supported in a cartridge assembly of the tool assembly. An anvil of the tool assembly has a threaded inner surface that defines a bore in a distal end portion of the anvil. The locking member is positioned for receipt in the bore of the anvil when the tool assembly is approximated about tissue a selected distance. The locking member has a threaded outer surface configured for threaded engagement with the threaded inner surface of the anvil. The locking member is operably coupled to a staple firing member, such that actuation of the staple firing member rotates the locking member. The tool assembly is configured to further approximate about the tissue in response to the rotation of the locking member within the bore of the anvil to maintain a gap distance between distal ends of the anvil and cartridge assembly.

In this description, the term “proximal” is used generally to refer to that portion of the device that is closer to a clinician, while the term “distal” is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term “clinician” is used generally to refer to medical personnel including doctors, nurses, and support personnel.

In FIG. 1, the surgical stapling device is illustrated generally as stapling device 10 and includes a handle assembly 12, an elongate body 14, and a staple reload 16. The elongate body 14 defines a longitudinal axis “X” and includes a proximal portion 14 a that is coupled to the handle assembly 12 and a distal portion 14 b that supports the staple reload 16. The staple reload 16 includes a proximal body portion 18 and a tool assembly 20. The proximal body portion 18 is releasably coupled to the distal portion 14 b of the elongate body 14. Alternately, the staple reload 16 and the elongate body 14 can be integrally formed such that the tool assembly 20 is fixedly attached to the elongate body 14. In other aspects, the tool assembly 20 may be directly attached to the distal portion 14 b of the elongate body 14.

The handle assembly 12 includes a housing 22 that defines a stationary handgrip 24 and supports a movable trigger 26 and a rotation knob 28. The rotation knob 28 is coupled to a distal portion of the housing 22 for rotation and supports the elongate body 14 such that rotation of the rotation knob 28 causes rotation of the elongate body 14 about the longitudinal axis “X”. The movable trigger 26 is supported by the housing 22 and can be pivoted in relation to the stationary handgrip 24 to actuate the tool assembly 20. In embodiments, the rotation knob 28 also supports an articulation knob 30 that can pivot or rotate about an axis perpendicular to the longitudinal axis “X” to articulate the tool assembly 20 from a position aligned with the longitudinal axis “X” to a position misaligned with the longitudinal axis “X”. Although illustrated as being a manually operated handle assembly 12, it is envisioned that the handle assembly 12 may be electrically or pneumatically powered, and may be adapted for use or coupled to a robotic surgical system.

FIGS. 2-7 illustrate the tool assembly 20 which includes an anvil 34 and a cartridge assembly 36 movably coupled to one another. Each of the anvil 34 and the cartridge assembly 36 includes a proximal portion 34 a, 36 a and a distal portion 34 b, 36 b. The proximal portion 34 a of the anvil 34 is coupled to the proximal portion 36 a of the cartridge assembly 36 by a pivot member 38 such that the tool assembly 20 can pivot between an open position (FIG. 2) and a first, approximated position (FIG. 4A). In embodiments, the cartridge assembly 36 includes a channel 40 that defines a longitudinal slot 42 (FIG. 3) and a staple cartridge 44 having a tissue contact surface 46. The staple cartridge 44 defines a plurality of staple pockets 48 and is received within the longitudinal slot 42 of the channel 40. In some embodiments, the staple cartridge 44 is adapted to be released from the channel 40 after firing of the stapling device 10 and replaced with a new or loaded staple cartridge 44. Each of the staple pockets 48 is configured and dimensioned to receive a staple 70. In embodiments, the staple cartridge 44 has a tissue guide portion 50 that is angled away from the anvil 34 in the distal direction.

The anvil 34 defines a tissue engaging surface 52 (FIG. 2) and includes a distal end portion 34 b that is angled from the tissue engaging surface 52 of the anvil 34 towards the cartridge assembly 36 at an obtuse angle. The angled distal end portion 34 b of the anvil 34 forms a dissecting tip 54. In embodiments, the dissecting tip 54 is spaced from the tissue guide portion 50 of the staple cartridge 44 when the tool assembly 20 is in the clamped position and extends along an axis that is substantially parallel to an axis defined by the tissue guide portion 50. Alternately, the dissecting tip 54 may have other configurations.

The dissecting tip 54, or any suitable location of the distal end portion 34 b of the anvil, defines a bore 56 therein. In embodiments, the anvil 34 is devoid of the dissecting tip 54 while still having the bore 56. The bore 56 in the distal end portion 34 b of the anvil 34 defines an axis that extends transversely relative to a longitudinal axis of the anvil 34. The dissecting tip 54 has a circular inner surface 58 that defines the bore 52. The inner surface 58 has a threaded, first segment 58 a (FIGS. 4A and 4B) disposed closer to the tissue-engaging surface 52 of the anvil 34, and a non-threaded, second segment 58 b disposed closer to an outer surface of the anvil 34. The threaded, first segment 58 a is configured to threadedly engage a threadform of a locking member 60 of the tool assembly 20, as will be described.

The tool assembly 20 also includes a drive assembly that includes a resilient firing shaft 62, a clamping member 64, and a sled 66. The firing shaft 62 may be fabricated from a plurality of elongated laminates and has a proximal end portion (not explicitly shown) operably coupled to the trigger 26 (FIG. 1), such that an actuation of the trigger 26 translates the firing shaft 62 through the elongate body 14 (FIG. 1.) The firing shaft 62 has a distal end portion 68 abutting or otherwise coupled to the sled 66 for translating the sled 66 through the cartridge assembly 36. As known in the art, the firing shaft 62 can be moved from a retracted position to an advanced position, in response to an actuation of the trigger 26, to advance the actuation sled 66 through the tool assembly 20 to sequentially eject the staples 70 from the staple cartridge 44.

The clamping member 64 may be coupled to the firing shaft 62 in such a manner that allows for advancement therewith for a selected distance, and independent movement of the firing shaft 62 relative to the clamping member 64 thereafter. The clamping member 64 is configured to advance with the firing shaft 62 the length of a slot 74 (FIGS. 2 and 3) in the anvil 34 to close the tool assembly 20, whereupon the clamping member 64 is released from the firing shaft 62, allowing the firing shaft 62 to continue its advancement independently of the clamping member to eject the staples 70.

The tool assembly 20 includes a tether 72 (FIG. 3), a locking member 60, and a biasing member 88. The tether 72 may be a flexible ribbon, a band, or the like, and has a proximal end portion 72 a and a distal end portion 72 b. The proximal end portion 72 a of the tether 72 is coupled to the sled. In some embodiments, the proximal portion of the tether 72 defines a hole 80 through which a protuberance 82 of the sled 66 is received, thereby coupling the tether 72 to the sled 66. The distal end portion 72 b of the tether 72 is coupled to the locking member 60 in such a manner that translation of the tether 72 causes a rotation of the locking member 60.

The locking member 60 is positioned in a distal end of the longitudinal slot 42 (FIGS. 3 and 3A) of the channel 40 and extends through an opening 84 in a distal end of the staple cartridge 44. The locking member 60 has a base or barrel portion 86 and an extension 89 protruding upwardly from the barrel portion 86. The barrel portion 86 of the locking member 60 is captured within the tissue guide portion 50 of the staple cartridge 44 to prevent the locking member 60 from translating transversely relative to the longitudinal axis of the staple cartridge 44. The barrel portion 86 has a rounded outer surface about which the distal end portion 72 b of the tether 72 is wrapped. The distal end portion 72 b of the tether 72 b may be fixed or otherwise coupled to the outer surface of the barrel portion 86 via an adhesive, a fastener, or any other suitable fastening mechanism. Therefore, rotation of the locking member 60 in a first rotational direction, indicated by arrow “A” in FIG. 6, translates the tether 72 (e.g., pulls the tether 72 distally), and retraction of the tether 72 rotates the locking member 60 in a second rotational direction, indicated by arrow “B” in FIG. 6.

With reference to FIGS. 2-4 and 7, the extension 89 of the locking member 60 has a cylindrical configuration and has a non-threaded, first portion 89 a disposed closer to the barrel portion 86, and a threaded second portion 89 b extending to the terminal end of the extension 89. The extension 89 of the locking member 60 is positioned for receipt in the bore 56 of the anvil 34, whereby the threaded second portion 89 b of the extension 89 threadedly engages the threaded first segment 58 a of the inner surface 58 of the anvil 34. When the threaded second portion 89 b of the extension 89 of the locking member 60 is engaged to the threaded first segment 88 a of the inner surface 58 of the bore 56 of the anvil 34, rotation of the locking member 60 approximates the distal end portions 34 b, 36 b of the anvil 34 and cartridge assembly 36.

With reference to FIGS. 3-7, the locking member 60 is spring-biased, in the direction indicated by arrow “A” in FIG. 7, by a biasing member 88 to coil the distal end portion 72 b of the tether 72 about the barrel portion 86 of the locking member 60. The biasing member 88 may be a torsion spring and is received in a cavity 90 defined by the barrel portion 86 of the locking member 60. In aspects, the biasing member 88 may be a mainspring. Other biasing members are also contemplated. The biasing member 88 has a first end 88 a captured within a slit 92 (FIGS. 3 and 3A) defined along a length of a post 94. The post 94 is fixed to the channel 40 of the cartridge assembly 36 and is received in the cavity 90 defined in the barrel portion 86 of the locking member 60. The biasing member 88 has a second end 88 b fixed to an annular, inner surface 96 of the barrel portion 86. It is contemplated that the locking member 60 and biasing member 88 are assembled while the biasing member 88 is in a loaded state, such that the biasing member 88 is set to exert a distally-oriented force on the tether 72 via the locking member 60.

In operation, when the surgical stapling device 10 is actuated to move the tool assembly 20 from the open position (FIG. 2) to a first, approximated position (FIGS. 4A and 4B) about tissue, the trigger 26 of the handle assembly 12 (FIG. 1) is actuated to move the firing shaft 62 in the direction indicated by arrow “C” in FIG. 4A to advance the clamping member 64 (FIG. 3). The clamping member 64 engages cam surfaces on the anvil 34 and/or cartridge assembly 36 to move the tool assembly 20 to the first, approximated position. The clamping member 64 is stopped from advancing (to the tissue-contacting surfaces/through the staple cartridge 44) of the tool assembly 20 by a distal limit of the slot 74 (FIG. 2) defined in the anvil 34. Accordingly, the firing shaft 62 and clamping member 64 are disengaged from one another, allowing the firing shaft 62 and the sled 66 to advance through the staple cartridge 44 independently of the clamping member 64 to eject staples from the staple cartridge 44.

Upon moving the tool assembly 20 to the first, approximated position, further advancement of the firing shaft 62 results in advancement of the sled 66 through the cartridge assembly 36 and into engagement with a plurality of pushers 73 (FIG. 3) to sequentially eject the staples 70 from the staple cartridge 44 into the tissue. As advancement of the sled 66 causes the ejection of the staples 70, the proximal end portion 72 a of the tether 72 is translated in a distal direction toward the distal end portion 72 b of the tether 72, easing tension in the tether 72. As the tension in the tether 72 is relieved, the loaded biasing member 88 is allowed to rotate the locking member 60 in the first direction, indicated by arrow “A” in FIG. 6, to coil the tether about the barrel 86 and maintain a selected tension in the tether 72. With the tool assembly 20 in the first, approximated position (FIGS. 4A and 4B), the threaded second portion 89 b of the extension 89 of the locking member 60 is in contact with the threaded first segment 58 a of the inner surface 58 of the dissection tip 54. Accordingly, the rotation of the locking member 60 caused by the biasing member 88 causes the threaded second portion 89 b of the extension 89 to threadedly engage the threaded first segment 58 a of the inner surface 58 of the dissection tip 54 and move linearly through the bore 56.

The threaded engagement between the extension 89 of the locking member 60 and the threaded first segment 58 a of the inner surface 58 of the dissection tip 54 further approximates the anvil 34 and cartridge assembly 36 toward a second, approximated position, as shown in FIG. 7, to lock the dissecting tip 54 to the distal end portion 36 b of the cartridge assembly 36. Engagement of the locking member 60 with the dissecting tip 54 of the anvil 34 prevents outward movement of the distal portion of the anvil 34 in relation to the distal portion of the cartridge assembly 36 beyond a predetermined distance to set a pre-determined tissue gap between the anvil 34 and cartridge assembly 36 at a distal end of the tool assembly 20.

Immediately prior to the tool assembly 20 entering the second, approximated position, the bottom-most threading of the threaded second portion 89 b of the extension 89 of the locking member 60 passes over the top-most threading of the threaded first segment 58 a of the inner surface 58 of the dissection tip 54, whereby the threaded second portion 89 b of the extension 89 of the locking member 60 disengages the threaded first segment 58 a of the inner surface 58 of the dissection tip 54 and engages the non-threaded second segment 58 b of the inner surface 58, such that further rotation of the locking member 60 fails to result in a further approximation of the tool assembly 20. In this way, as the sled 66 continues to advance to eject the staples 70 from the staple cartridge 44, the locking member 60 and the dissecting tip 54 maintain the tissue gap (FIG. 7) defined between the anvil 34 and the cartridge assembly 36 of the tool assembly 20 and avoid over compression or clamping of the tissue.

FIGS. 8 and 9 illustrate another embodiment of a locking member 160 for setting the tissue gap of a tool assembly 120. The tool assembly 120 is similar to tool assembly 20 and will only be described in detail to describe differences between the two assemblies. The tool assembly 120 includes an anvil 134 and a cartridge assembly 136. The anvil 134 includes a dissecting tip 154 that defines a bore 156 therein. The cartridge assembly 136 includes a staple cartridge 144 that that supports a plurality of staples 170. A firing shaft 162 and a sled 166 are provided for advancing the staples 170 from the staple cartridge 144.

The staple cartridge 144 includes a flexible, looped band 172 operably interconnecting the sled 166 and the locking member 160. The looped band 172 defines a plurality of apertures 174 spaced along the length of the looped band 172. One aperture in a proximal end portion 172 a of the looped band 172 receives a pin 182 extending from the sled 166, thereby coupling the sled 166 and the looped band 172. The proximal end portion 172 a of the looped band 172 is wrapped about a proximal post 180 a (FIG. 8) extending upwardly from a channel 140 of the cartridge assembly 136. The looped band 172 has a distal end portion 172 b wrapped about a base portion 186 of the locking member 160.

The base portion 186 of the locking member 160 has a plurality of circumferentially spaced protuberances 182 configured for receipt in respective apertures 174 of the looped band 172. The base portion 186 of the locking member 160 is rotatably supported on a first, distal post 180 b that extends upwardly from a distal end of the channel 140 of the cartridge assembly 136. A second, distal post 180 c of the channel 140 is engaged to an outer surface of the distal end portion 172 b of the looped band 172 to maintain the distal end portion 172 b of the looped band 172 tightly wound about the locking member 160. The looped band 172 is rotatable about the first distal post 180 b and the proximal post 180 a to rotate the base portion 186 of the locking member 160 about the first distal post 180 b in response to movement of the sled 166 within the staple cartridge 144. As the looped band 172 is rotated within the staple cartridge 144, the protuberances 182 of the locking member 160 are sequentially received in the respective apertures 174 in the looped band 172. In some aspects, rather than the locking member 160 having protuberances 182 received in the respective apertures 174 in the looped band 172, the distal end portion 172 b of the looped band 172 may be frictionally engaged with an outer surface of the locking member 160. Alternately, other known techniques or devices may be used to couple the looped band 172 to the base portion 186 of the locking member 160.

The locking member 160 has an extension 189 extending from the base portion 186. The extension 189 has a threaded outer surface 190 positioned for receipt in the bore 156 of the anvil 14, whereby the threaded outer surface 190 of the extension 189 threadedly engages a threaded inner surface 158 that defines the bore 156 in the anvil 134.

The tool assembly 120 functions in a similar manner to the tool assembly 20. More specifically, after the tool assembly 120 moves from the open position to the first, approximated position, advancement of the firing shaft 162 causes the sled 166 to advance through the cartridge assembly 136 and into engagement with a plurality of pushers 173 to sequentially eject the staples 170 from the staple cartridge 144 into the tissue. Due to the sled 166 being coupled to the looped band 172, advancement of the sled 166 causes the looped band 172 to travel about the first distal post 180 b and the proximal post 180 a of the channel 140 along a looped path, thereby rotating the locking member 160.

In the first, approximated position of the tool assembly 120, the threaded outer surface 190 of the extension 189 of the locking member 160 is in contact with the threaded inner surface 158 in the dissection tip 154 of the anvil 134. Accordingly, the rotation of the locking member 160 via the looped band 172 causes the threaded outer surface 190 of the extension 189 of the locking member 160 to threadedly engage the threaded inner surface 158 of the dissection tip 154 and move linearly through the bore 156.

Rotation of the extension 189 of the locking member 160 drives a further approximation of the anvil 134 and cartridge assembly 136 toward the second, approximated position to lock the dissecting tip 154 to the distal portion of the cartridge assembly 136. Engagement of the locking member 160 with the dissecting tip 154 of the anvil 134 prevents outward movement of the anvil 134 in relation to the cartridge assembly 136 beyond a predetermined distance to set a pre-determined tissue gap between the anvil 134 and cartridge assembly 136 at a distal end of the tool assembly 120.

Immediately prior to entering the second, approximated position, the bottom-most threading of the threaded outer surface 190 of the extension 189 passes over the top-most threading of the threaded inner surface 158 of the anvil 134, whereby the threaded outer surface 190 disengages the threaded inner surface 158, such that further rotation of the locking member 160 fails to result in a further approximation of the tool assembly 120. In this way, as the sled 166 continues to advance to eject the staples 170 from the staple cartridge 144, the locking member 160 and the dissecting tip 154 of the anvil 134 cooperate to maintain the tissue gap defined between the anvil 134 and the cartridge assembly 136 of the tool assembly 120.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of this disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A tool assembly comprising: an anvil having a proximal portion and a distal portion, the distal portion defining a bore therein; a cartridge assembly having a proximal portion and a distal portion, the proximal portion of the cartridge assembly pivotally coupled to the proximal portion of the anvil; a sled slidably received in the cartridge assembly and configured to move from a proximal position to a distal position to advance staples from the cartridge assembly; and a locking member rotatably supported on the distal portion of the cartridge assembly and positioned for receipt in the bore, wherein the locking member is operably coupled to the sled, such that advancement of the sled from the proximal position toward the distal position rotates the locking member relative to the bore to approximate the distal portions of the anvil and cartridge assembly.
 2. The tool assembly of claim 1, wherein the locking member has an extension having a threaded outer surface, and the bore in the distal portion of the anvil is defined by a threaded inner surface configured to threadedly engage the threaded outer surface of the extension of the locking member.
 3. The tool assembly according to claim 2, wherein the anvil and cartridge assembly are movable between an expanded position, in which the extension of the locking member is spaced from the bore in the anvil, and a first approximated position, in which the threaded outer surface of the extension of the locking member is engaged with the threaded inner surface of the anvil.
 4. The tool assembly according to claim 3, wherein the anvil and cartridge assembly are configured to move from the first approximated position to a second approximated position in response to rotation of the locking member while the threaded outer surface of the locking member is engaged with the threaded inner surface of the anvil.
 5. The tool assembly according to claim 1, further comprising a tether having a proximal end portion coupled to the sled, and a distal end portion disposed about the locking member, such that the advancement of the sled rotates the locking member via the tether.
 6. The tool assembly according to claim 5, wherein the locking member has a barrel portion rotatably supported in the cartridge assembly, and the distal end portion of the tether is fixed about the barrel portion.
 7. The tool assembly according to claim 6, further comprising a biasing member received in the barrel portion and coupled to the cartridge assembly, wherein the biasing member is configured to urge the tether in a distal direction.
 8. The tool assembly according to claim 5, wherein the locking member is spring-biased to urge the tether in a distal direction.
 9. The tool assembly according to claim 5, wherein the tether is a looped band defining a plurality of apertures, the locking member having a plurality of circumferentially spaced protuberances configured for receipt in the corresponding plurality of apertures.
 10. The tool assembly according to claim 9, wherein the sled has a pin extending therefrom and received in an aperture of the plurality of apertures, such that the advancement of the sled moves the band along a looped path.
 11. The tool assembly of claim 1, wherein the distal portion of the anvil has a tissue dissector, the tissue dissector defining the bore.
 12. A surgical stapling device, comprising: a handle assembly including a trigger; an elongate body extending distally from the handle assembly; a drive shaft having a proximal end portion operably coupled to the trigger and a distal end portion; and a tool assembly coupled to a distal portion of the elongate body, the tool assembly including: an anvil having a proximal portion and a distal portion, the distal portion of the anvil defining a bore therein; a cartridge assembly having a proximal portion and a distal portion, the proximal portion of the cartridge assembly pivotally coupled to the proximal portion of the anvil between an expanded position and an approximated position; a tether having a proximal end portion coupled to the distal end portion of the drive shaft, and a distal end portion; and a locking member rotatably supported on the distal portion of the cartridge assembly and positioned for receipt in the bore, wherein the distal end portion of the tether is disposed about and coupled to the locking member, such that when the cartridge assembly and anvil are in the approximated position, advancement of the drive shaft rotates the locking member relative to and within the bore to approximate the distal portions of the anvil and cartridge assembly.
 13. The surgical stapling device according to claim 12, wherein the locking member has an extension having a threaded outer surface, the bore in the distal portion of the anvil being defined by a threaded inner surface configured to threadedly engage the threaded outer surface of the extension of the locking member when the anvil and cartridge assembly are in the approximated position.
 14. The surgical stapling device according to claim 13, wherein in the expanded position, the extension of the locking member is spaced from the bore in the anvil, and in the approximated position, the threaded outer surface of the extension of the locking member is engaged with the threaded inner surface of the anvil.
 15. The surgical stapling device according to claim 12, wherein the locking member has a barrel portion rotatably supported in the cartridge assembly and having the distal end portion of the tether fixed thereabout.
 16. The surgical stapling device according to claim 15, wherein the tool assembly further includes a biasing member received in the barrel portion and coupled to the cartridge assembly, the biasing member being configured to urge the tether in a distal direction.
 17. The surgical stapling device according to claim 12, wherein the locking member is spring-biased to urge the tether in a distal direction.
 18. The surgical stapling device according to claim 12, wherein the tether is a looped band defining a plurality of apertures, the locking member having a plurality of circumferentially spaced protuberances configured for receipt in the corresponding plurality of apertures.
 19. The surgical stapling device according to claim 12, wherein the tool assembly further includes a sled slidably received in the cartridge assembly and interconnecting the distal end portion of the drive shaft and the proximal end portion of the tether, the sled configured to move from a proximal position to a distal position to advance staples from the cartridge assembly in response to an actuation of the trigger.
 20. The surgical stapling device according to claim 19, wherein the locking member is configured to rotate in response to movement of the sled between the proximal and distal positions. 